Stop start, good or bad

[Submariner1]

i dont like it ,most modern engines stop pretty much in the same place on flywheel ,ring gear so much stop start wears starter ring gear starter and other stuff , i cant think of a reason why i would want these items to wear out faster than previous models . and what of the carbon footprint of producing those items against the fuel saving, if i am stuck in long traffic lines i,am able to reach down to the key and turn the damn thing off .until they do away with that simple devise !!!!!!!!

A guy I know in F1, said he thought it was one of the worst engineering concepts that has come to market in his lifetime. Purely to pander to the mfg’s eco figures.
His take was its bad for the longevity aspect :-
1. Most bearing wear top and bottom end is at startup. Why increase that by 10 fold.
2. Hammers batteries, and solenoids
3. Horrible repetative wear on starter cogs and gear ring. He also said most engines come to rest at pretty much the same place give or take 2 or 3 cogs. So its concentrated wear in the same place.
4. Extra Bore wear, as the oil film has started to seperate down.
5. Crankshaft twisting, although minute, why multiply it by a factor of 10. In a normal car it would never show in normal engine life cycle but x10 or x20 ... only really long term tests will prove its not an issue.
6. Wear to auto transmission take up ... he lost me here. But basically if the engine is happily idling, there is no take up shock or something like that. If some component is happily rotating under very little duress, many of the bearings are effectively floating on a film of oil.
Turn off the engine, and that film is squeezed out, and the first “dry rotation” is not good for the engine.
7. More unecessary complex stuff to break e.g. overcoming the situation where engine power is cut and then needs to restart before the crank is stationery. Do you have a delay? .. or speed up certain elements to seemlessly mesh it. Fine when it works perfectly, but as it wears even the slightest out of sync coukd produce horrible wear.
8. Maybe OK if you have a 7 year mfg warranty, but on MBs do they really care if it dies in year 6?
(IMO Of course they dont give a rats!).

My take, its hard enough to keep these Lovelies running sweetly, with no repairs.
Why take on a load of complex extra stuff thats harmful to the engine and delivers relatively no real world benefit. Or if it does save some folks some petrol, is it enough to outweigh some huge repair bill down the track?
Even as an old codger ... if one has to spend money on these new super toys .. at least get something that helps you every day.
Like Auto parking ... its fantastic! Even if you are an ace parker, this helps avoid kerb scuffs, parking dinks, and reduces stress.

What I really dont like as a second purchaser is I have no idea if the first original owner, fastidiously turned it off every time?
Be interested if STAR could report .. No of starts from original day one? And if so could that be reset? I.e. “clocked”.

When I see figures like an average engine will start 50,000 times in its lifetIme and a SS will start 500,000 ... ; my stupid logic is thats 450,000 more starts or Nine times the wear!

I wont sweat about it, as I will definitely get MB Teir one warranty on my next, no doubt “start stop” car!

 

[400ixl]

Very old thinking on the wearing. Much has been sorted for a decade and more and hence you see very very little in the way of issues even on taxis doing hundreds of starts a day for hundreds of thousands of miles.

I can understand that people don't like it, and switch it off, fair enough, but there is so much FUD spread about the technology it beggers belief.

 

[EmilysDad]

Very old thinking on the wearing. Much has been sorted for a decade and more and hence you see very very little in the way of issues even on taxis doing hundreds of starts a day for hundreds of thousands of miles......

A taxi's engine is likely to stay running most of the day

 

[KennyN]

A taxi's engine is likely to stay running most of the day

Unless it has S/S technology ,which most of them will have.

Most newish cars should have S/S tech and i dont think i have heard anyone having issues with the mechanical side of things , not saying it hasnt happened but it seems to be the electrical side of things and external influencing factors that prevent it from operating properly 100% of the time.

Kenny

 

[400ixl]

A taxi's engine is likely to stay running most of the day

Last time I checked they had to stop at traffic lights like the rest of use. Every Merc Taxi I have been in for years has left the stop start switched on, not seen one manually switch it off yet.

 

[LostKiwi]

Very old thinking on the wearing. Much has been sorted for a decade and more and hence you see very very little in the way of issues even on taxis doing hundreds of starts a day for hundreds of thousands of miles.

I can understand that people don't like it, and switch it off, fair enough, but there is so much FUD spread about the technology it beggers belief.

So the manufacturers have updated the laws of physics?
It's simple logic that if something is designed to be lubricated when running switching it off (hence also stopping the lubrication) means it will initially start with no lubrication. OK so they may have materials more resistant to wear now and better able to cope with the lack of lubrication but fundamentally a stop/start engine MUST wear more than the same engine without stop start.
Cam chains on MBs are more prone to jump teeth in start up than any other time simply because that's the point in time where it's under the most stress.

As far as I'm concerned stop start is another great solution to a problem we don't really have.

 

[ajlsl600]

i ,have my own thinking on such issues. and WONT be using stop start ,if i ever get to a model having it.simples. same applies to other stuff thats supposed to make my life easier,safer, i will be the judge of that...

 

[L John]

The first start of the day will cause most wear, subsequent cycles of the stop start system will be a lot less than the first start but it will cause more wear than if it had kept on running.
When stop start came on the market I thought it must have an electrical oil pump to at least try to keep the oil pressure but as far as I'm aware, that is not the case.

From the link I posted earlier...

So far the technology is available only in Miller’s high-end racing oils, but in relation to stop-start, it could also reduce wear during each re-start when the most wear takes place.

With low-friction bearing and lubrication technology in place the potential threat to engine life by stop-start systems should theoretically be overcome. But the current technology is still relatively new and only time will tell whether every car manufacturer has got it right.

So, current on the road stop starts don't have high end racing oils or low friction bearings.
Yup, time will tell who's right but as Lost Kiwi says, you can't change the laws of physics.
Maybe when the new tech oils and bearings are up to scratch, timing chains/belts are stronger, the starter motor has 'swing' to randomise the starter gear wear, etc. it might all be worthwhile. In the meantime you take your chances that they have got it right.
The good side is if you have stop start but you don't use it, your car should last much better than one without the built in stop start.
And as Sub said, buying a used one will be a lottery as you wouldn't know the type of use.
A bit like the motorway miles versus town miles is now.

 

[Capra]

A taxi's engine is likely to stay running most of the day

Taxis don't sit on the taxi rank with the engine running.

 

[Capra]

Can you change the default to off? Never liked stop/start. With regards to oil pressure, are valves/moving parts still not coated in lube?

 

[EmilysDad]

Taxis don't sit on the taxi rank with the engine running.

I'm no expert, but I've seen many taxis at the rank with the engine running.

 

[Capra]

I'm no expert, but I've seen many taxis at the rank with the engine running.

When there busy no doubt but not just after the school run lol.

 

[A.J.]

Taxis don't sit on the taxi rank with the engine running.

They definitely do around here and I don't suppose they are any different elsewhere in the country !!

 

[Capra]

W

They definitely do around here and I don't suppose they are any different elsewhere in the country !!

They park up all the time with engines off here, especially when there standing around drinking coffee.

 

[400ixl]

So the manufacturers have updated the laws of physics?
It's simple logic that if something is designed to be lubricated when running switching it off (hence also stopping the lubrication) means it will initially start with no lubrication. OK so they may have materials more resistant to wear now and better able to cope with the lack of lubrication but fundamentally a stop/start engine MUST wear more than the same engine without stop start.
Cam chains on MBs are more prone to jump teeth in start up than any other time simply because that's the point in time where it's under the most stress.

As far as I'm concerned stop start is another great solution to a problem we don't really have.

Yes, it will wear more, but if that wear is not to a point of any issue being generated then there is no concern as to the wear. By your logic you should never start your car as it will be wearing it out. Forums would be full of problems if stop start were causing any as you hear about the things that go wrong, not the things that don't.

Agree, outside of reducing emissions it was a solving a non existent problem. However emissions are a problem to some and as it does no extra harm in terms of failures to leave it on there's no point in stressing about it. Let people decide for themselves if it is a feature they want on or off based on their beliefs and conveniences / annoyances, claiming their world will blow up if they don't is scare mongering.

 

[mercedes13156]

Of course it will. Every time you start the engine oil pressure is zero as it's the engine itself that generates oil pressure when running. Thats the time when most wear occurs.

Modern oil when heated up is like greased water and will fall out of the engine towards the sump like a waterfall. So, surely with no oil pressure, the top end will become a fairly oil deprived part of the engine as the oil pressure takes a few seconds to build up again after the engine starts. Listen to the top end of a cold engine in the morning and count to five while the engine pumps oil back up to the valve lifters and the camshafts. A five second run with no appreciable oil over a two hour drive is acceptable, but what if the thing stops and starts every couple of hundred yards over a couple of hours in town?

 

[Capra]

Modern oil when heated up is like greased water and will fall out of the engine towards the sump like a waterfall. So, surely with no oil pressure, the top end will become a fairly oil deprived part of the engine as the oil pressure takes a few seconds to build up again after the engine starts. Listen to the top end of a cold engine in the morning and count to five while the engine pumps oil back up to the valve lifters and the camshafts. A five second run with no appreciable oil over a two hour drive is acceptable, but what if the thing stops and starts every couple of hundred yards over a couple of hours in town?

It is like this because of the 0-30w rating?

 

[mercedes13156]

Yes! I'd imagine it is. I just poured a five litre bottle of 0/30W into my Kuga at the weekend. I nearly poured it over the edge of the funnel because it came out so fast.

 

[Capra]

Yes! I'd imagine it is. I just poured a five litre bottle of 0/30W into my Kuga at the weekend. I nearly poured it over the edge of the funnel because it came out so fast.

Not like the old Castrol GTX of the 90's then!!

 

[Botus]

check out youtube for a US bloke training muppets all about modern oils....

at one point he says BM cars won't run properly unless you run the thin **** because the oil and the crank vibration damper argue with each other